There are many kinds of boxes or cartons known in the art, that are used for holding goods for storage and transportation. These known boxes are made of various materials, such as cardboard, wood, metal, and plastics. However, all of the known boxes have, respectively, various disadvantages, such as moisture immersion, high cost, non-foldability, or too heavy. Particularly, none of the known foldable boxes is suitable for all environmental conditions, such as sunshine or hot environment, wet or humid conditions, cold or frozen conditions, and stacking-up with heavy load. Therefore, there is a need or demand for a durable box which can be used in any kinds of environment in which a box would be used. At the same time, the box must be cost efficient or economical, easily foldable, easily transportable, reusable, light weight, moisture resistant or moisture free, washable, and capable of stacking-up to bear heavy load for a relatively long period of time. The box should also be recyclable.
At present, no single box can meet all of these requirements. Most of one-piece board of foldable boxes are made of cardboard, waxed cardboard, or thin plastics because thick plastic boards cannot so easily folded. Such boxes usually utilize laminate layers or fillers to reinforce the side and end walls or corners of the box for better support. However, the support surfaces or tops are limited, i.e., relatively narrow. Therefore, the support is not strong enough to provide stable support for stacking-up boxes that are heavily loaded for a relatively longer time. Under certain bad environments, the multi-layers or fillers that stand side-by-side can be easily softened or weakened by the direct and strong sunshine or moisture. Such boxes are disclosed, for instance, in U.S. Pat. No. 4,129,247 to McCall; U.S. Pat. No. 4,068,795 to Forster; U.S. Pat. No. 2, 465,324 to De Mian; U.S. Pat. No. 4,770,338 to Tatusch; and U.S. Pat. No. 4,279,377 to Peeples et al.
The normal locking system for the boxes are tab and slot engagements that are not deadly locked. For example, the inset tabs and the slots are used in U.S. Pat. No. 4,733,916 to Seufert; and U.S. Pat. No. 3,708,103 to Evants. The barbed tabs are used in U.S. Pat. No. 3,991,932 to Carmel et al. Such locks can be easily released or unlocked without notice. Most of these locks are designed for cardboard material which is relatively soft and flexible. Thus, the locks cannot hold the box panels together once the material of the box looses its strength because of moisture immersion or merely worn-out.